A Time Division Duplex (TDD) mode which is one of two major fundamental duplex systems has gained increasing attention along with a constantly increasing bandwidth demand of broadband mobile communications. In the TDD system, the same frequency resource is used for both uplink-downlink transmission, and uplink-downlink signals are transmitted in different timeslots. In common TDD systems including a Time Division Synchronized Code Division Multiple Access (TD-SCDMA) which is a third generation (3G) mobile system, and a TD-SCDMA Long Term Evolution (TD-LTE) system which is a four generation (4G) mobile communication system, uplink-downlink timeslots are allocated statically or semi-statically, and a common practice is to determine and keep an allocation proportion of uplink-downlink timeslots unchanged according to a type of cell and a general service proportion in the course of network planning. This is a relatively simple practice and also effective in the context of a macro cell with large coverage. Along with the development of technologies, more and more low power base stations including a pico cell, a Home NodeB, etc., have been deployed to provide small local coverage, and in such cells, there are a lower number of users and significantly changing service demands of the users, so a proportion demand of uplink-downlink services of the cells are changing dynamically. Although an online change to a proportion of uplink-downlink timeslots of a cell is also supported, for example, in the TD-LTE standard, a complicated signaling flow and a configuration period of time are necessitated thus lowering the performance of the system while failing to trace a real-time service change condition.
Some more dynamic TDD uplink-downlink configuration solutions have gained attention.
In a specific temporal cycle, there are four types of sub-frames, particularly sub-frames fixedly used for downlink transmission, sub-frame fixedly used for uplink transmission, and sub-frame flexibly allocated for uplink or downlink transmission. Referring to FIG. 1, the temporal cycle is a radio frame (which is illustrated only as an example, but another temporal cycle is also possible), where sub-frames #0 and #5 are fixed downlink sub-frame, sub-frames #2 and #7 are fixed uplink sub-frame, sub-frames #1 and #6 are special sub-frame (which can also be allocated as fixed sub-frames), and other sub-frames (#3, #4, #8 and #9) are sub-frame flexibly allocated for uplink or downlink transmission. For the last type of sub-frames, a base station can dynamically configure them dependent upon a real-time service demand and channel condition to accommodate a dynamic change in service demand.
For the TDD system, bundling and multiplexing technologies are used for a Hybrid Automatic Repeat request (HARQ), that is, ACK/NACK of multiple downlink sub-frames is fed back over a Physical Uplink Control Channel (PUCCH). For the multiplexing technology, the ACK/NACK status is related to both information bit to be fed back over the PUCCH and a PUCCH resource index. For the bundling technology, although the ACK/NACK status is related to only the information bit to be fed back over the PUCCH, the PUCCH resource index is mapped in the same manner as in the multiplexing technology in order to avoid PUCCH resource confliction between users. Typically there is no confliction occurring with PUCCH resource mapping if a uniquely corresponding HARQ timing scheme is used for an uplink-downlink configuration scheme.
In a dynamic system, the use of a new HARQ scheme (also including the reuse of an HARQ scheme corresponding to a specific configuration of a non-dynamic system) is required in order to accommodate a flexible change in uplink-downlink sub-frame configuration. Also in order to ensure backward compatibility, it is necessary to semi-statically configure an existing uplink-downlink configuration and to use an HARQ scheme corresponding thereto for user equipments of lower releases. Thus different HARQ schemes may be used for users of R11 and later releases from users of lower releases. There may be PUCCH resource confliction for these two types of users if the existing PUCCH format 1/1a/1b resource index nPUCCH(1) mapping method is used.
The principle of nPUCCH(1) mapping will be introduced below.
nPUCCH(1) can be configured by a higher layer for use in an Uplink Scheduling Request (SR), Semi-Persistent Scheduling (SPS) and other situations without Physical Downlink Control Channel (PDCCH) scheduling; and also can be bound with nCCE (an index of the first CCE, in a corresponding downlink sub-frame, used for a PDCCH) for use in situations with PDCCH scheduling.
Typically in order to avoid confliction of higher layer configured nPUCCH(1) with calculated nPUCCH(1), ACK/NACK/SR resources are divided by the parameter NPUCCH(1) into two sections. The higher layer configured nPUCCH(1) satisfies nPUCCH(1)<NPUCCH(1), and the calculated nPUCCH(1) satisfies nPUCCH(1)≧NPUCCH(1).
Noted the higher layer configured nPUCCH(1) is configured by the base station itself, so nPUCCH(1)≧NPUCCH(1) will not be precluded.
For the sake of a concise description, a set of ACK/NACK/SR resources indicated by higher layer signaling is simply referred to as a higher layer configured section; and a set of ACK/NACK resources bound with nCCE is simply referred to as a predefined section or a calculation section. No boundary between the two sections is defined in the standard, but typically the higher layer section precedes the calculation section with nPUCCH(1) being a boundary between them, and for the sake of a simplified subsequent description, this typical scenario will be applicable throughout as an example. However in fact, respective solutions will not be limited to the typical scenario.
In order to lower the number of resource fragments, nPUCCH(1) is calculated for firstly a sub-frame and then a section (the section actually refers to a range of values of nCCE, and sections are typically allocated dependent upon the number of PDCCH symbols, that is, the number of sections is equal to the number of PDCCH symbols). As illustrated in FIG. 2, there is a nPUCCH(1) mapping method (the uplink-downlink configuration 1).
As specified by the protocol:
For the non-dynamic TDD system, with ACK/NACK bundling or ACK/NACK multiplexing, with M=1, the UE transmits HARQ-ACK using the PUCCH resource number nPUCCH(1) in the sub-frame n, where:
In the sub-frame n−k, if there is either a PDSCH indicated by a PDCCH(s) or a PDCCH indicating uplink Semi-Persistent Scheduling (SPS) resource releasing, where kεK with K being a set {k0, k1, . . . kM−1}including M elements and the value of M being related to an uplink-downlink configuration (as depicted in Table 1), then the UE firstly selects a value of p from the set {0,1,2,3} to satisfy Np≦nCCE<Np+1, where nCCE is the index of a first Control Channel Element (CCE), in the sub-frame n−km, used for a PDCCH, where km is the lowest value in the set K and satisfies such a condition that the UE detects the PDCCH in the sub-frame n−km. Np=max{0,└[NRBDL×(NscRB×p−4)]/36┘} is defined, and then ACK/NACK resource index used for an ACK/NACK feedback is nPUCCH(1)=(M−m−1)×Np+m×Np+1+nCCE+NPUCCH(1), where NPUCCH(1) is a higher layer configured parameter, and NPUCCH(1) is an ACK/NACK/SR resource index, M is the number of downlink sub-frames corresponding to the same uplink feedback sub-frame, m is the index of a downlink sub-frame, nCCE is the index of a first CCE, in the sub-frame n−km, used for a PDCCH, and Np=max{0,└[NRBDL×(NscRB×p−4)]/36┘} with NRBDL being the number of downlink PRBs and NscRB being the number of sub-carriers in a PRB, that is 12, and p being a value in {0,1,2,3}.
For a PUCCH in a multi-port transmission mode, a PUCCH resource of the second antenna port is indexed by incrementing a PUCCH resource of the first antenna port by 1, that is, nPUCCH(1)=(M−m−1)×Np+m×Np+1+nCCE+NPUCCH(1)+1; and
Moreover for two aggregated carriers and the current sub-frame for an ACK/NACK feedback corresponding to only one downlink sub-frame, for the carrier in a multi-codeword transmission mode, a PUCCH resource corresponding to the second codeword is indexed by incrementing a PUCCH resource corresponding to the first codeword by 1, that is, nPUCCH(1)=(M−m−1)×Np+m×Np+1+nCCE+NPUCCH(1).
In the sub-frame n−k (kεK), if there is only a PDSCH transmitted without being indicated by a PDCCH, then nPUCCH(1) is configured jointly by a higher layer and Table 2.
TABLE 1Downlink association set index K: {k0, k1, . . . kM−1} for TDDUL-DLSub-frame nConfiguration01234567890——6—4——6—41——7, 64———7, 64—2——8, 7, 4, 6————8, 7, 4, 6——3——7, 6, 116, 55, 4—————4——12, 8, 7, 116, 5, 4, 7——————5——13, 12, 9, 8, 7, 5, 4, 11, 6———————6——775——77—
TABLE 2PUCCH Resource Index for Downlink Semi-Persistent SchedulingValue of ‘TPC command for PUCCH’nPUCCH(1,p)‘00’The first PUCCH resource indexconfigured by the higher layers‘01’The second PUCCH resource indexconfigured by the higher layers‘10’The third PUCCH resource indexconfigured by the higher layers‘11’The fourth PUCCH resource indexconfigured by the higher layers
For TDD ACK/NACK multiplexing, with M>1, in the sub-frame n, nPUCCH,i(1) is defined as an ACK/NACK feedback resource index derived from the sub-frame n−ki, and HARQ-ACK(i) is defined as particular information fed back by ACK/NACK/DTX corresponding to the sub-frame n−ki, where kiεK (as depicted in Table 1) and 0≦i≦M−1:
For a PDSCH in the sub-frame n−ki or a PDCCH indicating SPS resource releasing, where kiεK, the ACK/NACK feedback resource index is nPUCCH,i(1)=(M−i−1)×Np+i×Np+1+nCCE,i+NPUCCH(1), where pε{0,1,2,3}, Np≦nCCE<Np+1 is satisfied, Np=max{0,└[NRBDL×(NscRB×p−4)]/36┘}, nCCE,i is the index of a first CCE, in the sub-frame n−ki, used for a PDCCH, and NPUCCH(1) is a higher layer configured parameter.
For a PDSCH without being indicated by a PDCCH in the sub-frame n−ki, nPUCCH(1) is configured jointly by a higher layer and Table 2.
Comparing the ACK/NACK bundling and ACK/NACK multiplexing solutions, both of their fundamental principles are the same, that is, the relationship between nPUCCH(1) and nCCE,i is created based upon nPUCCH,i(1)=(M−i−1)×Np+i×Np+1+nCCE,i+NPUCCH(1). Their difference lies in that in ACK/NACK bundling, i is a determined value which is i=m, and km is the lowest value in the set K and satisfies such a condition that the UE detects the PDCCH in the sub-frame n−km; and in ACK/NACK multiplexing, i corresponds in one-to-one to a downlink sub-frame, that is, each downlink sub-frame corresponds to nPUCCH,i(1).
This application is primarily focused upon how to configure nPUCCH,i(1), and particularly how to use nPUCCH,i(1) in ACK/NACK bundling and ACK/NACK multiplexing is not a focus of this application, and the use of the existing system solution is recommended, so ACK/NACK bundling will not be further distinguished from ACK/NACK multiplexing in the following description.
For an SR and the situation of SPS without being PDCCH scheduling, a PUCCH format 1/1a/1b resource is configured by the base station itself, and confliction between users of different releases can be avoided by the base station from occurring; and
For the situation of a PDSCH with PDCCH scheduling or a PDCCH indicating SPS resource releasing, a PUCCH format 1/1a/1b resource is determined in a predefined scheme, that is, the relationship between nPUCCH,i(1) and nCCE,i of the PUCCH format 1/1a/1b resource is specified in the protocol and both the base station and the user equipment obtain nPUCCH,i(1) by referring to this relationship. In the dynamic system, there are uses of different releases. When there are different HARQ schemes of the different releases, mapping of an ACK/NACK resource as in the prior art may result in ACK/NACK resource confliction between the users.